Human tumor cell growth inhibition by nontoxic anthocyanidins, the pigments in fruits and vegetables.

Anthocyanidins, the aglycones of anthocyanins, impart brilliant colors in many fruits and vegetables. The widespread consumption of diets rich in anthocyanin and anthocyanidins prompted us to determine their inhibitory effects on human cancer cell proliferation. Five anthocyanidins, cyanidin (1), delphinidin (2), pelargonidin (3), petunidin (4) and malvidin (5), and four anthocyanins, cyanidin-3-glucoside, cyanidin-3-galactoside, delphinidin-3-galactoside and pelargonidin-3-galactoside were tested for cell proliferation inhibitory activity against human cancer cell lines, AGS (stomach), HCT-116 (colon), MCF-7 (breast), NCI H460 (lung), and SF-268 (Central Nervous System, CNS) at 12.5-200 microg/mL concentrations. The viability of cells after exposure to anthocyanins and anthocyanidins was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric methods. The anthocyanins assayed did not inhibit cell proliferation of cell lines tested at 200 microg/mL. However, anthocyanidins showed cell proliferation inhibitory activity. Malvidin inhibited AGS, HCT-116, NCI-H460, MCF-7 and SF-268 cell growth by 69, 75.7, 67.7, 74.7 and 40.5%, respectively, at 200 microg/mL. Similarly, pelargonidin inhibited AGS, HCT-116, NCI H460, MCF-7 and SF-268 cell growth by 64, 63, 62, 63 and 34%, respectively, at 200 microg/mL. At 200 microg/mL, cyanidin, delphinidin and petunidin inhibited the breast cancer cell growth by 47, 66 and 53%, respectively. This is the first report of tumor cell proliferation inhibitory activity by anthocyanidins.